For Attack; look for these: Flash Sagittario, Wyvang, Balro(Those two are from the Ultimate Synchrome DX set Defense and Stamina, so you may want to buy two if you can to synchrome them).
So you can create: Flash___ /Wyvang Wyvang GB145/H145/W145(From Samurai Ifraid)/S130(If you have any of those)R2F.
For Defense; look for these: Reviser, Killerken, Duo, and a Jade Jupiter or Blitz Unicorno/Striker for its rubber defense tip. Revsier and Killerken can be obtained from the DX set I mentioned above. Duo comes from the original Ultimate DX set, which contains numerous useful parts.
So you can create: Duo Bull/Killerken Reviser(Reviser on top) BD145(Yes, very good) CS/RSF/RDF/RB.
For Stamina; look for these: Duo/Phantom/Genbull Genbull(Only obatainable through Zero-G Random Booster Vol. 3), Griffin Dragoon 2-pack with SA165,(Only through Hasbro), and an Evil Befall can be useful for EWD. If you are willing to purchase the ZRGRB3 you may want to purchase a Bereserker Begirados for SR200.
So you can make: Duo/Phantom/Reviser Dragoon(Killerken can also work)SA165WD/EWD or Genbull Genbull SR200TB.
For Balance; look for these: You'd need Genbull, Dragooon, Samurai Ifraid, Diablo(Optional).
So you can make: Genbull Dragooon F230CF, amazing combo; or Diablo Bull BD145RF/R2F/LF, I'd go with the ladder.
Overall: Genbull F230TB, Griffin Dragoon two pack, Ultimate DX set(Containing Duo, L-Drago Guardian, and Wing Pegasus), Samurai Ifraid, and if you have enough for budget 2 Ultimate Synchrome DX Defense and Stamina sets. And of course MF's and MSF's.
Hope this helped.
Edit: And of course if you need Zero-G combos or Limited Combos; just tell me.